462.6325 MHz interference. DMR?

[LeoG]

With my Wouxun XSK20G+ when I first started out I never heard this with my Naygoya UT72G antenna.  I moved up to the Midland MTXA26 and I started to hear this interference mostly on 462.625, but it bleeds through many more channels.  Sometimes I would hear it in my driveway, but usually I would hear it as I drove up my street to go to work.  As I got further from my house it goes away.  But it shows up in other areas not just near my house.  Seems to show up near cell phone towers but not always, I don't think it's from cell service transmitters.

I put up my antenna on my house and of course I get this interference.  Right now I'm putting encode tones in to kill it on the repeater stations I usually tune into .575, .625.  For the most part it works but not always.  So tonight I put the radio into VFO mode and found it seems to center at 462.6325 and it's continuous for the most part.  I also noticed that there seems to be 2 different signals on the same frequency.  The weaker one is continuous and the other comes and goes but is stronger.  I did a video of it and actually caught the 2nd signal.

At this point I'm trying to figure out what it is and if I can do something about it.  Looked up the frequency and it doesn't seem to correspond to anything but figured I'd ask and maybe it's something that can be there.  The interference is really annoying and makes it much more difficult to listen to the repeaters.

 

Here's the video and at 15-25 seconds you can see in the power meter and hear in the sound the 2nd signal.  You can see how it bleeds over into the GMRS channels

 

[Lscott]

You can try searching the frequency database. If you’re lucky it belongs to a licensed user in your area.

https://digitalfrequencysearch.com/index.php

[Guest]

32 minutes ago, LeoG said:

With my Wouxun XSK20G+ when I first started out I never heard this with my Naygoya UT72G antenna.  I moved up to the Midland MTXA26 and I started to hear this interference mostly on 462.625, but it bleeds through many more channels.  Sometimes I would hear it in my driveway, but usually I would hear it as I drove up my street to go to work.  As I got further from my house it goes away.  But it shows up in other areas not just near my house.  Seems to show up near cell phone towers but not always, I don't think it's from cell service transmitters.

I put up my antenna on my house and of course I get this interference.  Right now I'm putting encode tones in to kill it on the repeater stations I usually tune into .575, .625.  For the most part it works but not always.  So tonight I put the radio into VFO mode and found it seems to center at 462.630 and it's continuous for the most part.  I also noticed that there seems to be 2 different signals on the same frequency.  The weaker one is continuous and the other comes and goes but is stronger.  I did a video of it and actually caught the 2nd signal.

At this point I'm trying to figure out what it is and if I can do something about it.  Looked up the frequency and it doesn't seem to correspond to anything but figured I'd ask and maybe it's something that can be there.  The interference is really annoying and makes it much more difficult to listen to the repeaters.

 

Here's the video and at 15-25 seconds you can see in the power meter and hear in the sound the 2nd signal.  You can see how it bleeds over into the GMRS channels

 

We have a near identical sound  on 725.  Sounds like a diesel generator and it goes on 24hrs a day and has a radius of around 100miles. 

[nokones]

Sounds like the Midland MXT26 is a better performing antenna than that other antenna.

[LeoG]

5 minutes ago, nokones said:

Sounds like the Midland MXT26 is a better performing antenna than that other antenna.

Yes, I agree 100%.  It transmits and receives better than the Nagoya.  But it also came with the problems I described.  6dBi gain compared to 3dBi gain of the UT72G.  And now 7.2dBi gain of my base antenna.

[Guest]

12 minutes ago, nokones said:

Sounds like the Midland MXT26 is a better performing antenna than that other antenna.

The mxt26 is by far a much better antenna than the ut72 for sure.   

[LeoG]

54 minutes ago, Lscott said:

You can try searching the frequency database. If you’re lucky it belongs to a licensed user in your area.

https://digitalfrequencysearch.com/index.php

No luck, but it gives a pretty wide range.  Can't enter the actual frequency.  Just the base frequency and a +/- 1MHz offset, doesn't accept decimal offsets.

 

[LeoG]

34 minutes ago, WRXP381 said:

The mxt26 is by far a much better antenna than the ut72 for sure.   

Which is exactly why I have one

[marcspaz]

One of the reasons there are such strict rules with GMRS radio performance is because emergency service all around the country share this RF space with GMRS.  in my area, there are a few fire departments that use 462 MHz for UHF digital data links.  They run 24/7 and the one closest to my house freaked out for awhile, splashing GMRS.

 

If you have access to a Kraken SDR, track it down and get the owner to fix it.

[TrikeRadio]

31 minutes ago, marcspaz said:

One of the reasons there are such strict rules with GMRS radio performance is because emergency service all around the country share this RF space with GMRS.  in my area, there are a few fire departments that use 462 MHz for UHF digital data links.  They run 24/7 and the one closest to my house freaked out for awhile, splashing GMRS.

Why do emergency services send vital data on frequencies that sit between publicly used FRS / GMRS frequencies? I mean yes radios should not be leaking out transmissions where they should not but every kid at the park with a walmart radio could be on the frequencies above and below where emergency data is being transmitted.

 

[LeoG]

After playing around more I actually think the frequency is 462.6325, not that it really matters that much, but the signal strength seems stronger and more stable.

I put the TD-H3 on the frequency by VFO and didn't hear the signal using the base antenna with an adapter.  The adapter has a pretty small coax on it.  I found another one at a lower frequency that was stronger and the H3 could receive it. 

 

Corrected the original post

[LeoG]

1 hour ago, marcspaz said:

One of the reasons there are such strict rules with GMRS radio performance is because emergency service all around the country share this RF space with GMRS.  in my area, there are a few fire departments that use 462 MHz for UHF digital data links.  They run 24/7 and the one closest to my house freaked out for awhile, splashing GMRS.

 

If you have access to a Kraken SDR, track it down and get the owner to fix it.

Ya, no such luck that I have a KrakenSDR

[marcspaz]

3 hours ago, TrikeRadio said:

Why do emergency services send vital data on frequencies that sit between publicly used FRS / GMRS frequencies? I mean yes radios should not be leaking out transmissions where they should not but every kid at the park with a walmart radio could be on the frequencies above and below where emergency data is being transmitted.

 

I wish I knew... it seems like a bad idea, but it has been working so far.  If I were to take a WAG at it, I would assume its related to the availability of inexpensive and improved tech, combined with a lot of government radio being moved to higher UHF frequencies, and demand from private persons increased.

 

However, its the other way around.  They put FRS and GMRS in the government allotted spectrum.  Emergency services and LMR occupied the space before the PRS.

[LeoG]

Seems to be an epidemic up near another repeater I frequent.  The seem to think it is a pair of cranes lifting large beams that are communicating with each other.  They don't know if it's automatic adjustment between the two cranes or the guys running them communicating with each other or others.  But they know since the 2nd crane got there the interference has been brutal for them on the 575

I'm not sure if I get any of that, but I do get bleed over from my problem onto the 575 along with the worse interference on the 625

[WRYC373]

In response to this i think its fun to remember the history of our frequencies. 

GMRS came first as a solution for family sized businesses needing LMR like capabilities in the 60s allowing 2 pairs per license and it made sense to put it in the relatively unused at the time UHF portion of LMR/EMCOM.  Then in the 70s power was increased to 50W and the pair rule abandoned and in the 80s business license issuing was suspended. Note many radios of this era were either just Part90 or dual Part90/95e. And almost no Part95e repeaters existed to my knowledge.

Then FRS came around and thus was born a simple small easy to use solution for most American's radio needs supplanting finnicky CB HTs. Then hybrid FRS/GMRS radios came out from Motorola  and other radio manufacturers and really made a mess of things until the 2017 ruling that opened the final can of worms.

In short GMRS has always been in a weird spot. 

On 7/15/2024 at 2:46 AM, marcspaz said:

 

I wish I knew... it seems like a bad idea, but it has been working so far.  If I were to take a WAG at it, I would assume its related to the availability of inexpensive and improved tech, combined with a lot of government radio being moved to higher UHF frequencies, and demand from private persons increased.

 

However, its the other way around.  They put FRS and GMRS in the government allotted spectrum.  Emergency services and LMR occupied the space before the PRS.

 

[LeoG]

Digital is a newer tech.  It isn't compatible with analog to share the same frequencies.

[WRYZ926]

On 7/19/2024 at 11:27 PM, LeoG said:

Digital is a newer tech.  It isn't compatible with analog to share the same frequencies.

Both share the same frequencies on the amateur radio bands all of the time. It is quite common to have a 2m or 70cm repeater setup for both analog and digital. The most common digital mode around me is DMR. My local club has 3 70cm repeaters and all are setup for analog and DMR.

Digital on GMRS frequencies is a moot point since it is not allowed.

[MarkInTampa]

2 hours ago, WRYZ926 said:

Both share the same frequencies on the amateur radio bands all of the time. It is quite common to have a 2m or 70cm repeater setup for both analog and digital. The most common digital mode around me is DMR. My local club has 3 70cm repeaters and all are setup for analog and DMR.

Digital on GMRS frequencies is a moot point since it is not allowed.

Not allowed doesn't mean it is being done. In my area somebody is running an encrypted DMR repeater that has driven 462.700 useless for everybody in the area. It's been reported countless times over the last two years but it's still there.

On the other hand there are also two pretty strong public repeaters, one runs analog/NXDN and the other analog/P25. The info to use them are public if you want to use digital. 95% of all traffic is analog, occasionally folks complain about the digital traffic but its so infrequent they get over it.